612 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



over the opposing gravitating force ; and this gain of 229 pounds 

 is expended in adding 229 pounds of water to the protuberance of 

 the sea, and when this has been done, then the forces are again in 

 equilibrio. This result is readily calculated from the two angles 

 at which these forces are brought to bear. Then, of course, it is 

 plain to be seen that the level of the sea is disturbed by change of 

 its specitic gravity, and if only a part has its specific gravity 

 changed Avhile the main body remains neutral or unchanged, then 

 that part v/hich alone is affected must act for itself. 



But let us resort to figures to show the propelling power of the 

 Gulf stream. Maury, in his "Physical Geography of the Sea," 

 speaking Of the Gulf stream, saj^s : "There is off Hattcras, and 

 even as high up as the Grand Banks, a difference of temperature 

 between the waters of the Gulf stream and the ocean upon either 

 side, of from 20° to 30°," Let us take a point anywhei-e between 

 these two points — say directly opposite the port of New York — 

 and suppose the temperature of the Gulf stream to be 25° Fah. 

 above the temperature of the ocean upon either side of it. Water, 

 at a temperature of 55° raised to 80 degrees, changes its specific 

 gravity by expansion l-282d part. The centrifugal protuberance 

 of the ocean, at this point of estimate, is about ten miles, or three 

 miles less than at the equator. Now, as the waters of the Gulf 

 stream at this point are 1-28 2d part lighter than the ocean upon 

 either side, it is also l-282d part of ten miles of protuberance above 

 the proper level for water of its temperature and specific gravity. 

 The ten miles of protuberance is 52,800 feet, and l-282d part 

 of this is 187 feet: consequently the colder Avater, or main body 

 of the ocean, is holding the Gulf stream up, at this point of esti- 

 mate, 187 feet above the true level for Avater of its specific gravity. 

 Or, in other words, if the ocean at this point v/ere of the same 

 temperature as the Gulf stream, then its protuberance level would 

 be 187 feet lower than it now is; consequently the Gulf stream is 

 to all intents and purposes, running down hill towards the pole, 

 and this hill at the capes of Florida is about 250 feet high, and at 

 the New York latitude 187 feet high. This is the cause of the 

 Gulf stream, and is also the main cause of all permanent oceanic 

 currents, both warm and cold. 



